package util;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

/**
 * 使用DES加密与解密，可对byte[]，String类型进行加密与解密
 * 密文可使用String，byte[]存储.
 *  方法： 
 *  void getKey(String strKey)从strKey的字条生成一个Key
 *  String getEncString(String strMing)对strMing进行加密，返回String密文 
 *  String getDesString(String strMi)对strMin进行解密，返回String明文
 *  byte[] getEncCode(byte[] byteS)byte[]型的加密 
 *  byte[] getDesCode(byte[] byteD)byte[]型的解密
 */
public class DES {

	public static Key key;

	// 根据参数生成KEY
	public static void getKey(String strKey) {
		try {
			KeyGenerator _generator = KeyGenerator.getInstance("DES");
			_generator.init(new SecureRandom(strKey.getBytes()));
			key = _generator.generateKey();
			_generator = null;
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	// 加密String明文输入，String密文输出
	public static String getEncString(String strMing) {
		byte[] byteMi = null;
		byte[] byteMing = null;
		String strMi = "";
		BASE64Encoder base64en = new BASE64Encoder();
		try {
			byteMing = strMing.getBytes("UTF-8");
			byteMi = getEncCode(byteMing);
			strMi = base64en.encode(byteMi);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			base64en = null;
			byteMing = null;
			byteMi = null;
		}
		return strMi;
	}

	// 解密 以String密文输入，String明文输出
	public static String getDesString(String strMi) throws Exception {
		BASE64Decoder base64De = new BASE64Decoder();
		byte[] byteMing = null;
		byte[] byteMi = null;
		String strMing = "";
		try {
			byteMi = base64De.decodeBuffer(strMi);
			byteMing = getDesCode(byteMi);
			strMing = new String(byteMing, "UTF-8");
		} catch (Exception e) {
			throw e;
		} finally {
			base64De = null;
			byteMing = null;
			byteMi = null;
		}
		return strMing;
	}

	// 加密以byte[]明文输入，byte[]密文输出
	private static byte[] getEncCode(byte[] byteS) {
		byte[] byteFina = null;
		Cipher cipher;
		try {
			cipher = Cipher.getInstance("DES");
			cipher.init(Cipher.ENCRYPT_MODE, key);
			byteFina = cipher.doFinal(byteS);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			cipher = null;
		}
		return byteFina;
	}

	// 解密以byte[]密文输入，以byte[]明文输出
	// @param byteD
	// @return

	private static byte[] getDesCode(byte[] byteD) throws Exception {
		Cipher cipher;
		byte[] byteFina = null;
		try {
			cipher = Cipher.getInstance("DES");
			cipher.init(Cipher.DECRYPT_MODE, key);
			byteFina = cipher.doFinal(byteD);
		} catch (Exception e) {
			throw e;
		} finally {
			cipher = null;
		}
		return byteFina;
	}

	// 加密字符串，返回String的密文
	public static String getCryptograph(String str) {
		getKey("MYKEY11ERDCDVEIOKPUE");// 生成密匙
		String strEnc = getEncString(str);
		return strEnc;
	}

	// 把String 类型的密文解密
	public static String getDisplay(String cryptograph) throws Exception {
		String strEnc = null;
		try {
			getKey("MYKEY11ERDCDVEIOKPUE");
			strEnc = getDesString(cryptograph);
		} catch (Exception e) {
			throw e;
		}
		return strEnc;
	}

	public static void main(String[] args) throws Exception {
		String s = getCryptograph("FOCS");
		System.out.println(s);
		
		System.out.println(getDisplay(s));
	}
}
